Every spring, approximately 100 breeding pairs of black-crowned night-herons arrive at the Smithsonian’s National Zoo in Washington, D.C. The herons have been nesting here since before the zoo was established in 1889, yet we still do not know where they spend the winter.

Last August, the Smithsonian’s Migratory Bird Center and the Bird House began a pilot study to unravel this mystery. Three adult herons from the rookery were fitted with satellite transmitters. The satellite transmitters emit signals for 2 hours, daily during migratory periods and every other day the remaining months.

Signals from the transmitters are picked up by satellites passing overhead and relayed to processing centers where the data is collected and processed to provide coordinates of the bird’s location.

Meanwhile, it remains to be seen whether the current locations of these birds are temporary stops or final destinations. One thing is certain, we know more now than we did last summer!

JoGayle (in green) left the breeding site on August 13 but remained in the D.C. area, near the Georgetown waterfront. Unfortunately, as of December 22, for unknown reasons, the transmitter stopped receiving locations.

Russ (in red) left the breeding site on September 22. Over the next 6 days, it made its way to Charlotte County, FL, a distance of 1400 km. It remained there since December 30, after which it travelled another 150 km to the Dade-Collier Training and Transition Airport. This transmitter also stopped receiving locations as of January 14, 2014.

Clive (in blue) left the breeding site on August 15 but remained in the D.C. area for another two months. On October 16 it started to move: first going to the eastern shore of the Chesapeake Bay and staying for about three weeks, then heading south on November 6. It has been in northern Florida, 20 km southwest of Jacksonville, FL since November 20. For unknown reasons, this transmitter also stopped receiving locations as of December 22.